Numbering the elements of a list

Question

From a vector q={Gamma,x,y}, I would like to create the following corresponding list : qn={1,2,3}.

Other example, if I have q={Gamma,x,y,theta}, I would like to retrieve qn={1,2,3,4}.

Thank you for your help.

Is there a better way than Table[i, {i, 1, Length[q]}]?

Thank you

Answer 1

This will give what you are looking for

q = {Gamma, x, y, theta};
Range[Length[q]]
(* {1, 2, 3, 4} *)

Or, with less typing,

Range@Length@q
(* {1, 2, 3, 4} *)

Answer 2

As @Jason already commented, the usual form would be

Range @ Length @ q;

If your goal is to number the list you can do

> Transpose[{Range @ Length @ q, q}]

{{1, Gamma}, {2, x}, {3, y}, {4, theta}}

or use MapIndexed

MapIndexed[List, q]

{{Gamma, {1}}, {x, {2}}, {y, {3}}, {theta, {4}}}